Positive skin tests in late reactions to radiographic contrast media.

In the last few years delayed reactions several hours after the injection of radiographic and contrast materials (PRC) have been described with increasing frequency. The authors report two observations on patients with delayed reactions in whom intradermoreactions (IDR) and patch tests to a series of ionic and non ionic PRC were studied. After angiography by the venous route in patient n degree 1 a biphasic reaction with an immediate reaction (dyspnea, loss of consciousness) and delayed macro-papular rash appeared, whilst patient n degree 2 developed a generalised sensation of heat, persistent pain at the site of injection immediately and a generalised macro-papular reaction after 24 hours.